US4602485A - Refrigeration unit including a hot gas defrosting system - Google Patents

Refrigeration unit including a hot gas defrosting system Download PDF

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US4602485A
US4602485A US06/601,014 US60101484A US4602485A US 4602485 A US4602485 A US 4602485A US 60101484 A US60101484 A US 60101484A US 4602485 A US4602485 A US 4602485A
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Prior art keywords
hot gas
refrigerant
compressor
stop valve
circuit
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US06/601,014
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Yuji Fujimoto
Masayuki Aono
Tsutomu Takei
Tetuo Nakano
Teiji Nakabayashi
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Daikin Industries Ltd
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Daikin Industries Ltd
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Priority claimed from JP7177083A external-priority patent/JPS59197764A/ja
Priority claimed from JP7177383A external-priority patent/JPS59197767A/ja
Priority claimed from JP7177183A external-priority patent/JPS59197765A/ja
Application filed by Daikin Industries Ltd filed Critical Daikin Industries Ltd
Assigned to DAIKIN INDUSTRIES, LTD. reassignment DAIKIN INDUSTRIES, LTD. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: AONO, MASAYUKI, FUJIMOTO, YUJI, NAKABAYASHI, TEIJI, NAKANO, TETUO, TAKEI, TSUTOMU
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
    • F25B47/02—Defrosting cycles
    • F25B47/022—Defrosting cycles hot gas defrosting

Definitions

  • This invention relates to a refrigeration unit or more particularly to a refrigeration unit having a compressor, condensers and an evaporator and capable of performing a selection between three operation, i.e., a cold storage, and/or a refrigeration, and a defrosting operation.
  • a cold storage operation is a control for any temperatures higher than -5° C.--6° C.
  • the "refrigeration” operation is a control for any lower temperatures lower than -5° C.--6° C.
  • a system which performs defrosting by introducing hot gas into an evaporator at the defrost time is previously known as shown in the specification and drawings of U.S. Pat. No. 4,353,221.
  • a three-way valve TV is provided on the high pressure gas line B of a compressor A, one outlet of said three-way valve being connected to a condenser C and the other outlet to a hot gas by-pass passage H bypassing said condenser C, receiver R and expansion valve EV, said hot gas by-pass H being connected to the inlet side of said evaporator E, said hot gas by-pass passage H being provided with a pressure regulating valve V 1 which throttles its opening by sensing the pressure rise at the outlet side of said evaporator E, a pressure regulating valve V 2 which opens by sensing the increase in high said pressure being provided between said hot gas bypass passage H and said condenser C.
  • said three-way valve TV is switched on to the hot gas bypass passage H to use hot gas in said evaporator E for defrosting and said two pressure regulating valves V 1 , V 2 control their respective openings so that neither suction pressure nor discharge pressure does not rise abnormally.
  • a hot gas bypass passage is connected to the high pressure gas line which connects the discharge side of a compressor A with the inlet side of condensers C 1 ,C 2 so as to bypass said condensers C 1 ,C 2 , a receiver R and expansion valve EV, said hot gas bypass line H being connected to the inlet side of the evaporator, said hot gas bypass line H being provided, near at its connection to said high pressure gas line B, with a hot gas valve HV which controls hot gas bypass quantity to said evaporator E, the capacity of said evaporator E being controlled by adjustment of said hot gas valve HV so as to control the supply air temperature consequently, the hold temperature in the chilled range.
  • the defrosting operation performed by circulating hot gas through said evaporator E may be adopted and performed.
  • the low side pressure of refrigerant becomes high and the refrigerant circulation quantity becomes that much larger and on the other hand
  • the low side refrigerant pressure becomes lower and the refrigerant circulation quantity becomes small.
  • the refrigerant circulation quantity around the defrosting circuit varies with the operating condition immediately before entering defrosting operation, which results in the following problems.
  • the hot gas circulation quantity through said evaporator E varies with the operating condition immediately before said defrosting, which makes an appropriate defrosting operation impossible.
  • the purpose of this invention is to optimize, at the defrosting operation, the refrigerant circulation quantity around the defrosting circuit so as to provide appropriate defrosting and ensure said appropriate defrosting irrespective of the operating condition immediately before said defrosting operation.
  • this invention comprises and is characterized by a cooling circuit which returns hot gas discharged from the compressor through the condensers and the evaporator back to the compressor; a hot gas bypass passage which supplies hot gas to said evaporator, by passing said condensers; a hot gas valve which opens and closes said hot gas bypass passage; a defrost circuit which supplies hot gas from said hot gas bypass passage to said evaporator by means of said hot gas valve and returns it to the compressor; a first stop valve which is provided downstream of said condensers in said cooling circuit and closes for the pumping-
  • the refrigeration unit is run, at the defrosting operation, so as to circulate constant quantity refrigerant around the defrost circuit and thereby is able to perform the optimum defrosting operation irrespective of the operating condition immediately before entering the defrosting operation.
  • FIG. 1 is the refrigerant piping diagram showing No. 1 embodiment of the refrigeration unit of this invention
  • FIG. 2 is the wiring diagram thereof
  • FIG. 3 is the flow chart for the defrosting operation thereof
  • FIG. 4 is the refrigerant piping diagram showing No. 2 embodiment of the refrigeration system of this invention.
  • FIG. 5 is the wiring diagram thereof.
  • FIG. 6 is the flow chart for the defrosting operation thereof
  • FIG. 7 is the wiring diagram of the major part of another example of No. 2 embodiment.
  • FIG. 8 is the flow chart for the defrosting operation of FIG. 7,
  • FIG. 9 is the refrigerant piping diagram showing No. 3 embodiment of the refrigeration unit of this invention.
  • FIG. 10 is the wiring diagram for the major part thereof.
  • FIG. 11 is the flow chart for defrosting operation thereof
  • FIG. 12 and FIG. 13 are the refrigerant piping diagrams of conventional refrigeration units.
  • FIG. 1 Shown in FIG. 1 is a typical embodiment of the refrigeration unit of the invention for the marine container application.
  • numeral 1 is a compressor
  • numeral 2 an air-cooled condenser
  • numeral 3 a water-cooled condenser
  • numeral 4 an evaporator
  • numeral 5 a thermostatic expansion valve with a feeler bulb 51 and each of these components is connected by the piping 6 to constitute a cooling circuit which cools the hold air by said evaporator 4.
  • numeral 7 is a receiver integrated with an accumulator
  • numeral 7a the receiver portion thereof
  • numeral 7b the accumulator portion thereof
  • numeral 8 a drier
  • numeral 9 a liquid indicator
  • numeral 10 are the fans mounted on said evaporator 4 and numeral 11 the fans attached to said air-cooled condenser 2.
  • a hot gas bypass passage 20 is connected to the high pressure gas line 6a connecting the delivery side of said compressor 1 to the inlet side of said air-cooled condenser so as to supply hot gas discharged from the compressor 1 directly to said evaporator 4, bypassing said condensers 2, 3, the receiver portion 7a of said receiver 7 and said thermostatic expansion valve 5, the outlet side of said hot gas bypass passage 20 being connected to the low pressure liquid line 6b between said expansion valve 5 and said evaporator 4, a hot gas valve 21 being provided on the junction part of this hot gas bypass passage 20 with said high pressure gas line 6a to control hot gas bypass flow and adjust the capacity in the cold storage operation, and the entire hot gas volume bypassed through said hot gas valve 21 is supplied through said hot gas bypass passage 20 to said evaporator 4 to form the defrost circuit.
  • FIG. 1 is provided, downstream of said liquid indicator 9 with a first stop valve 30 in solenoid type which closes at the stop signal of the refrigeration operation or cold storage operation and the start signal of the defrosting operation in order to enable the pumping-down operation and seal refrigerant in the liquid reservoir portion including said condenser, 2, 3, the receiver portion 7a of the receiver 7.
  • a first stop valve 30 in solenoid type which closes at the stop signal of the refrigeration operation or cold storage operation and the start signal of the defrosting operation in order to enable the pumping-down operation and seal refrigerant in the liquid reservoir portion including said condenser, 2, 3, the receiver portion 7a of the receiver 7.
  • a constant quantity refrigerant flow-out control mechanism 40 is provided to supply constant quantity refrigerant out of the entire refrigerant thus sealed in said liquid resorvoir into the defrost circuit for the defrosting operation, that is, said defrost circuit comprising the compressor 1, the hot gas valve 21, the hot gas bypass passage 20, the evaporator 4 and the accumulator portion 7b of the receiver 7.
  • Said hot gas valve 21 is primarily a motorized three-way type proportional control valve capable of controlling its opening, from 0 to 100%, to said hot gas bypass passage 20 in proportion with the voltage applied and is constructed so as to adjust the capacity by controlling hot gas volume bypassed to said evaporator 4 and supply the entire refrigerant volume in circulation at defrosting to said hot gas passage 20 and be controlled by below described controller 22 and the auxiliary switch 2DX 2 of the defrost control circuit. Further, said hot gas valve 21 is PID controlled by the controller 22.
  • PID control proportional-plus-intergral-plus-derivative control
  • control signal is proportional with the sum of deviation signal, its integral and its derivative.
  • said constant quantity refrigerant flow-out control mechanism 40 is constructed to mount a second stop valve 41 in solenoid type, in the liquid reservoir portion, for the pumping-down operation by closing said first stop valve 30, so as to seal constant quantity liquid between the mounting position of said first stop valve 30.
  • said first stop valve 30 is mounted on the high pressure liquid line 6c at the inlet side of said expansion valve 5 and said second stop valve 41 on the high said liquid line 6c at the outlet side of said liquid indicator 9 so as to seal constant quantity refrigerant in the high pressure liquid line 6c between the two valves 30, 41 and pass thereof to the evaporator 4 by opening said first stop valve 30 with said second stop valve 41 left closed.
  • Said constant quantity of refrigerant set by said constant quantity refrigerant flow-out control mechanism 40 is to be set at the optimum so that the refrigeration operation or cold storage operation which follows the defrosting operation is always operable irrespective of the operating condition, and the defrosting operation does not take long.
  • constant quantity refrigerant flow-out control mechanism 40 is constructed by the high side liquid line 6c, said second stop valve 41 and said first stop valve 30, it may be constructed in the low pressure liquid line 6b, only if it is located downstream of condensers 2, 3, that is, downstream of the liquid reservoir. Further, said constant quantity refrigerant flow-out control mechanism 40 may be constructed by using a special piping or liquid reservoir in place of the refrigerant circuit liquid line.
  • a bypass passage 28 having a solenoid valve 26 and in-series connected capillary tube 27 is provided between the high pressure line 6c at the inlet side of said second stop valve 41 and the high pressure liquid line 6c at the inlet side of said first stop valve 30, by passing said second stop valve 41.
  • this bypass passage 28 is, as later described, to use in the cold storage operation when necessary. Further, since the outlet volume of said solenoid valve 26 at the bypass passage 28 is so small, it is negligible to said constant quantity refrigerant.
  • numeral 23 is a solenoid valve mounted on the suction gas line 6e which closes when energized and is arranged in parallel with a capilary tube 24.
  • this solenoid valve 23 is to return gaseous refrigerant to the compressor 1 through said capilary tube 24 by the close thereof and thereby reduce refrigerant circulation quantity.
  • Said reduction of refrigerant circulation quantity is for the purpose of protecting overloading due to the high temperature of the high pressure side which takes place, in case of a high ambient temperature, in the refirgeration or cold storage operation after defrosting operation or at the pull-down operation, and due to said reduction of refrigerant circulation the work of the compressor 1 is reduced and the high side pressure and the compressor motor current is lowered, thereby enabling the expansion of the operation range.
  • said solenoid valve 23 is arranged so as to close when the suction air temperature of the evaporator 4 is sensed by a sensor to have exceeded a certain temperature and open when said suction air temperature is sensed by a sensor to have fallen below said temperature, it may be controlled by the high side pressure or the low side pressure. It may be controlled also by the suction air temperature of the air-cooled condenser 2, that is, the ambient air temperature so as to close above a certain temperatures thereof and open below said temperature.
  • numeral 63L is a low pressure switch
  • numeral 63H a high pressure switch
  • numeral 63CL a high pressure control switch
  • numeral 63QL an oil pressure protection switch
  • numeral 63W a water pressure switch.
  • said hot gas valve 21 is arranged, as later described in FIG. 2, to be controlled by the output signal of said controller 22 and the start signal of the defrosting operation and said first stop valve 30 is closed for the pumping-down operation at the start signal of the defrosting operation. Further, the completion of the pumping-down operation and the start of the defrosting operation is controlled primarily by the low-pressure switch 63L.
  • the air pressure switch APS which senses the pressure drop across said evaporator 4 and a defrost timer 2D which sets the defrosting time for example at 12 hours are in use.
  • said air pressure switch APS is given priority over said defrost timer 2D and by the operation of said air pressure switch APS, said defrost timer 2D is reset.
  • the defrosting operation is completed by sensing the temperature of said low pressure gas line 6d by means of two thermostats 23D 1 , 23D 2 having different set temperature which are mounted on the lower pressure gas line 6d, for example, at the evaporator 4 outlet.
  • FIG. 2 Shown in FIG. 2 is a wiring diagram of the refrigeration unit as shown in FIG. 1, wherein the compressor motor MC, three indoor fan motors MF 1-1 , MF 1-2 , MF 1-3 corresponding to three fans 10 attached to said evaporator 4 and three out-door fan motors MF 2-1 , MF 2-2 , MF 2-3 corresponding to three fans 11 attached to said air-cooled condenser 2 are provided, the electric circuit of said electric machinery being connected to the power source by selecting either the low tension plug P 1 for 200 V/220 V or the high tension plug P 2 for 380-415 V/440 V and the control circuit of said controller 22 and various controls being connected, through a transformer Tr to said electric circuit.
  • the compressor motor MC three indoor fan motors MF 1-1 , MF 1-2 , MF 1-3 corresponding to three fans 10 attached to said evaporator 4 and three out-door fan motors MF 2-1 , MF 2-2 , MF 2-3 corresponding to three fans 11 attached to said air-
  • CB is a circuit breaker, OC an overcurrent relay, 2X 1 -2X 3 auxiliary relays and their contacts, 3-88 an on-off switch.
  • contacts having no reference symbols are the contacts that are switched over by the selection of said plug P 1 or P 2 , Y 1 , V 1 , G 2 and G 1 are the change-over switch between the refrigeration operation and the cold storage operation housed in said controller 22, Y 1 being a short-circuit line.
  • said controller 22 though not shown in FIG. 2, is provided with an input transformer, a power input unit, a sensor input unit, an operation input and output unit, a central processing unit and a relay output unit. And connected to said sensor input unit are, as shown in FIG. 1, the return sensor RS located on the suction side of the evaporator 4 for sensing the return air temperature from the hold and the supply air sensor SS located on the supply side of the evaporator 4 for sensing the supply air temperature to the hold.
  • a set point selector PS and an output display unit DP Connected to said operation input and output unit are a set point selector PS and an output display unit DP and connected to said relay out-put unit are the motorized portion 20M of said hot gas valve 21, the solenoid relay 20SS of said solenoid valve 23 of the embodiment of FIG. 1, auxiliary relays 2X 4 , 2X 5 , lamps AL, BL and the following relay circuit:
  • a circuit in-series consisting of a parallel circuit of normally-open contacts of auxiliary relays 2X 4 , 2DX 2 , and the solenoid relay 20LS 1 of said first stop valve 30 for the pumping-down operation (pumping-down control circuit).
  • a circuit in-series connected consisting of a parallel circuit of the contacts of the air pressure switch APS for signaling the start of the defrosting operation, the defrost timer 2D, the manual defrost switch 3D and the normally-open contacts of the defrost relay 2DX 1 ; the in-series circuit of two thermostat 23D 1 , 23D 2 for detecting the completion of the defrosting operation; a parallel circuit of said defrost relay 2DX 1 and a parallel circuit of the normally-closed contacts of the magnet switch 88c of the compressor motor MC and the self-holding contacts of the auxiliary relay 2DX 2 with the auxiliary relay 2DX 2 in-series connected (defrost control circuit).
  • CPD is a contact protection diode, GL and RL lamps and 3-30L a lamp switch.
  • the motorized portion 20M of said hot gas valve 21 is arranged to be switched over to be 100% open position by means of a direct circuit through the normally-open contacts of said auxiliary relay 2DX 2 which is provided separately of the control circuit of said controller 22.
  • the control of the hold air temperature is performed, based on the set temperature of the point selector PS of said controller 22 by on-off control of the compressor 1 at the signal of the retrun sensor RS in case of the refrigeration operation of below -5° C. set temperature and by controlling said hot gas valve 21 between 0-100% and bypassing the hot gas quantity corresponding to the respective opening at the signal of the supply air sensor SS in case of the cold storage operation of above -5° C. set temperature. Further in this case, it is also possible to conduct the cold storage operation using the bypass passage 28 by switching the manual change-over switch MS so as to close the second stop valve 41 and open the solenoid valve 26.
  • the defrosting operation is conducted as follows:
  • the defrost relay 2DX 1 is energized and said auxiliary relay 2X 4 deenergized to open said pumping-down control circuit and deenergize the solenoid relay 20LS 1 of said first stop valve 30 and close said first stop valve 30 for starting the pumping-down operation.
  • liquid refrigerant is sealed in the condensers 2, 3, the receiver portion 7a of the receiver 7 and the liquid line 6c extending to said first stop valve 30 and at the same time the low side pressure of the compressor 1 become lowered.
  • said low pressure switch 63L opens said on-off control circuit of the compressor motor MC and denergize the magnet switch 88c of said motor MC to stop the compressor 1 and complete the pumping-down operation.
  • volume of said defrost circuit is far larger than that of liquid refrigerant stored by said constant quantity refrigerant flow-out control mechanism.
  • liquid refrigerant quantity stored by said constant quantity refrigerant flow-out control mechanism is small, it can be completely evaporated by the heat capacity of the high side liquid line 6c itself and heat absorbed by said high side liquid line from the ambient air.
  • said low pressure switch 63L When the low side pressure rises, by this flow-out, above the set pressure of said low pressure switch 63L, said low pressure switch 63L goes on to start the compressor 1, said constant quantity refrigerant being circulated around the defrosting circuit and the defrosting operation being performed by hot gas flowing into the evaporator 4 through said hot gas bypass passage 20.
  • this defrosting operation is performed by using constant quantity refrigerant set by said constant quantity refrigerant flow-out control mechanism 40, it is possible to perform an optimum defrosting operation irrespective of the operating condition immediately before defrosting.
  • the thermostat 23D 1 whose setting temperature is lower of the two thermostats 23D 1 ,23D 2 mounted on the outlet side of the evaporator 4 operates, said defrost control circuit being opened, said defrost relay 2DX 1 being deenergized, the self-holding of the auxiliary relay 2DX 2 being released, said solenoid relays 20LS 1 , 20LS 2 being energized, said first stop valve 30 and second stop valve 41 or solenoid valve 26 being opened and the refrigeration unit returning to the refrigeration operation or the cold storage operation using opening control of the hot gas valve 21 by the controller 22.
  • said second stop valve 41 remains closed and only solenoid valve 26 opens.
  • the suction gas line 6e is provided, as already described, with a parallel circuit of said solenoid valve 23 and a capillary tube, said solenoid valve 23 being closed by detecting supply air temperature, high side pressure, low side pressure or the ambient air temperature, refrigerant circulated being throttled through the capillary tube 24.
  • the solenoid relay 20SS of said solenoid valve 23 is in-series connected with a parallel circuit of the normally-open contacts of the auxiliary relay 2X 5 and the thermostat 23A for detecting said supply air temperature through the normally-closed contacts of said defrost relay 2DX 1 , it is possible to operate at the reduced refrigerant circulation and expand the operation range at the operating condition of abnormally high ambient temperature and high side pressure.
  • said bypass passage 28 is utilized to reduce the liquid refrigerant flow and together with said capillary tube 24, reduce the refrigerant circulation for the expansion of the operation range.
  • the embodiment of FIG. 2 is constructed as follows to avoid the operation of the high pressure switch 63H and over-current relay OC due to the rise of the low side pressure and consequent rise of the high side pressure. That is, the magnet switch 88F of said indoor fan motors MF 1-1 ,MF 1-2 ,MF 1-3 is in-series connected, through the contacts of said delay timer 2F, with the normally-closed contacts of said auxiliary switch 2DX 2 .
  • a high pressure or low pressure switch having a pressure setting other than that of said high pressure or low pressure switch 63H, 63L is conceivable besides the delay timer 2F.
  • said constant quantity refrigerant flow-out control mechanism 40 of the above described embodiment is constructed so that a second stop valve 41 is provided upstream of said first stop valve 30, constant quantity refrigerant sealed between these two valves 30, 41 being released to the defrost circuit by opening said first stop valve 30.
  • said constant quantity refrigerant flow-out control mechanism 40 may also be constructed so that as shown in FIG. 4 a communication passage 42 is provided bypassing said first stop valve 30 so as to let the liquid reservoir in the cooling circuit communicate with the suction side of the compressor 1, said communication passage being provided with a third stop valve 43 in solenoid type which passes only constant quantity refrigerant of the refrigerant sealed in said liquid reservoir into the defrost circuit after the pumping-down operation.
  • the bypass passage 28 having a solenoid valve 26 and a capillary tube 27 of FIG. 1 is not necessary and therefor omitted in this embodiment.
  • Said communication passage 42 of FIG. 4 is also provided with a pressure reducing mechanism 44 primarily consisting of a capillary tube and connected, at one end thereof, to the high pressure liquid line 6c having said first stop valve 30 and at the other end thereof, to the low pressure gas line 6d.
  • a pressure reducing mechanism 44 primarily consisting of a capillary tube and connected, at one end thereof, to the high pressure liquid line 6c having said first stop valve 30 and at the other end thereof, to the low pressure gas line 6d.
  • Said first stop valve 30 may be mounted, as with the embodiment of FIG. 1, on the cooling circuit from the condenser 3 outlet to the evaporator 4 inlet, for example, on the low pressure liquid line 6b.
  • said third stop valve 43 is controlled so as to open at the completion of the pumping-down operation and close after constant quantity refrigerant has been passed.
  • the means of said control is by a low pressure switch 63L 2 other than the low pressure switch 63L 1 which detects the completion of the pumping-down and said switch 63L 2 goes "on” when the low side pressure falls below the pressure setting thereof and goes “off” when the low side pressure rises above pressure setting thereof. (See FIG. 5)
  • a timer 2D 2 may be also used for this purpose. (See FIG. 7)
  • said low pressure switch 63L 1 for detecting the completion of the pumping-down operation and said low pressure switch 63L 2 are hereafter called No. 1 low pressure switch and No. 2 low pressure switch, respectively.
  • Said No. 2 low pressure switch 63L 2 is mounted on the defrost control circuit described later in the wiring diagram and opens said third stop valve 43 when the compressor 1 is stopped by the off action of No. 1 low pressure switch 63L 1 and the pumping-down operation is completed, and closes said third stop valve 43 by detecting the pressure rise due to refrigerant flow-out of said liquid reservoir.
  • No. 1 low pressure switch 63L 1 also goes on by the pressure rise due to refrigerant flow-out of said communication passage 42, it is possible to start the compressor 1 simultaneously with the close of said third stop valve 43 by setting the going-on pressure thereof so as to coincide with the going-out pressure setting of No. 2 low pressure switch 63L 2 and also start the compressor 1 steadily before the closing of said third stop valve 43 by bringing the going-on pressure setting thereof below the going-out pressure setting of No. 2 low pressure switch 63L 2 .
  • FIG. 4 these components having no changes as compared with No. 1 embodiment are denoted by the same symbols and numeral 31 is an auxiliary bypass passage which bypasses at the cold storage operation certain quantity of hot gas irrespective of the opening of the hot gas valve 21 and improve the fluctuation of control accuracy due to the fluctuation of the opening of said hot gas valve 21 and is provided with a solenoid valve 32 which opens in the cold storage operation.
  • numeral 31 is an auxiliary bypass passage which bypasses at the cold storage operation certain quantity of hot gas irrespective of the opening of the hot gas valve 21 and improve the fluctuation of control accuracy due to the fluctuation of the opening of said hot gas valve 21 and is provided with a solenoid valve 32 which opens in the cold storage operation.
  • the solenoid relay 20LS 1 of said first stop valve 30 is in-series connected only with the normally-open contacts of the auxiliary switch 2X 4 .
  • the auxiliary relay 2DX 2 is in-parallel connected with the in-series connected circuit of the normally-closed contacts of No. 2 low pressure switch 63L 2 and the solenoid relay of said third stop valve 43.
  • the above constructed embodiment operates just as the afore described No. 1 embodiment.
  • the compressor 1 is stopped by the operation of No. 1 low pressure switch 63L 1 to complete the pumping-down operation
  • the auxiliary relay 2DX 2 is energized, the motorized portion 20M of said hot gas valve 21 is operated to fully open said hot gas valve 21, the indoor fan motors MF 1-1 , MF 1-2 , MF 1-3 being stopped, the solenoid relay 20LS 3 of said third stop valve 43 being energized through No. 2 low pressure switch 63L 2 to open said third stop valve 43, thereby refrigerant sealed at the pumping-down operation being passed, through said third stop valve 43, to the defrost circuit.
  • No. 1 low pressure switch 63L 1 goes on to start, as with No. 1 embodiment, the compressor 1 and continue the defrosting operation with constant quantity refrigerant.
  • No. 2 low pressure switch is in use as an on-off control means for said third stop valve 43 but the timer may be used for this purpose.
  • the wiring diagram is as shown in FIG. 7 and the flow chart of the defrosting operation is as shown in FIG. 8.
  • said timer 2D 2 is, as shown in FIG. 7, in parallel connected with the auxiliary relay 2DX 2 in the defrost control circuit, the timing contact of this timer 2D 2 being in series connected with the solenoid relay 20LS 3 of said third stop valve 43, an auxiliary relay 2X 7 being in-parallel connected with said solenoid relay 20LS 3 , the normally-closed contact of this auxiliary relay 2X 7 being in series connected with the magnet switch 88C in the compressor on-off control circuit of said compressor motor MC.
  • the solenoid relay 20LS 1 of said first stop valve 30 goes off at the start signal of the defrosting operation, to start the pumping-down operation, said magnetic switch 88C being deenergized by the off action of said low pressure switch 63L to stop the compressor 1, said auxiliary relay 2DX 2 being energized to fully open the hot gas valve 21, the indoor fan motors MF 1-1 ,MF 1-2 , MF 1-3 being stopped.
  • auxiliary relay 2X 7 is not always necessary. But by using said auxiliary relay 2X 7 , the compressor 1 is started after the counting of said timer 2D 2 is over and said third stop valve 43 closes. Therefore, it is possible to exactly operate the flow of constant quantity refrigerant by said third stop valve 43.
  • the constant quantity refrigerant control mechanism is constructed so that after the entire refrigerant is sealed in the liquid reservoir of the cooling circuit, constant quantity refrigerant is passed into the defrost circuit.
  • This constant quantity refrigerant control mechanism may be changed as follows: Though the pumping-down operation is started by the start signal of the defrosting operation, this changed version of the embodiment is constructed so that the compressor 1 is stopped to discontinue the pumping-down operation when the low side pressure has reached to a certain pressure level which is higher than the compressor 1 would reach at the completion of the normal pumping-down operation, thereby leaving constant quantity refrigerant in the defrost circuit.
  • this No. 3 embodiment employs, in addition to the low pressure switch 63L 3 which detects the completion of the normal pumping-down operation, a low pressure switch 63L 4 having a pressure setting higher than that of the low pressure switch 63L 3 and said low pressure switch 63L 4 is mounted, as shown in FIG. 10, in the on-off control circuit of the compressor motor MC described in No. 1 embodiment.
  • said low pressure switch 63L 3 is called No. 3 low pressure switch in order to distinguish from low pressure switches 63L 1 , 63L 2 , and the low pressure switch 63L 4 for use in said defrosting operation is called No. 4 low pressure switch.
  • the off-setting pressure of No. 4 low pressure switch 63L 4 is made higher than that of No. 3 low pressure switch 63L 3 , thereby refrigerant quantity remaining in the defrost circuit being decided. That is, refrigerant quantity corresponding to the pressure difference between the settings of two low pressure switches 63L 4 , 63L 3 is to remain in the defrost circuit.
  • the refrigerant piping system of No. 3 embodiment is the system wherein the second stop valve 41 and the bypass passage 28 having a solenoid valve 26 are removed from No. 1 embodiment as shown in FIG. 1 and at the same time, the system wherein the communication passage 42 having the third stop valve 43 is removed from No. 2 embodiment as shown in FIG. 4.
  • FIG. 10 being basically same with FIG. 2 and the detail having being explained above, only different points will be explained as follows:
  • the solenoid relay 20LS 1 of said first stop valve 30 is in-series connected with the normally-open contacts of the auxiliary relay 2X 4 .
  • the on-off control circuit of the compressor motor MC is constructed so as to consist of an in-series connected safety circuit of a compressor protection thermostat 49, over-current relay OC, a high pressure switch 63H, No. 3 low pressure switch 63L 3 , and an oil pressure protection switch 63QL; an in-parallel connected circuit of the normally-open contacts of the auxiliary relay 2DX 2 , the normally-closed contacts of the defrost relay 2DX 1 and No. 4 low pressure switch 63L 4 ; and the magnet switch 88C of the compressor motor MC.
  • the magnet switch 88C of said compressor motor MC is thus deenergized, said compressor 1 being stopped, said auxiliary relay 2DX 2 being energized by the closing of the normally-closed contacts of said magnet switch due to the deenergization thereof, the motorized portion 20M of said hot gas valve 21 operating to fully open said valve 21, said indoor fan motors MF 1-1 ,MF 1-2 ,MF 1-3 being simultaneously stopped.
  • the normally-open contacts of said auxiliary relay 2DX 2 which is in parallel connected with No.
  • a low pressure switch (similar to the low pressure switch 63L 4 ) which goes on when the low side pressure falls below the setting, and the normally-open contacts of the auxiliary relay 2DX 2 , the normally-closed contacts of the defrost relay 2DX 1 and No. 4 low pressure switch 63L 4 which are mounted on the on-off control circuit of said compressor motor have to be removed.
  • the opening control of the hot gas valve 21 are made by detecting the supply air temperature with a supply sensor SS and comparing with the temperature setting
  • a pressure sensor which detects the high side or low side pressure of refrigerant may be used for this purpose.
  • Said valve opening control may be made by detecting the temperature difference between return and supply air.
  • an air-cooled condenser 2 and a water-cooled condenser 3 are jointly used in the embodiment, single air-cooled condenser 2 or water-cooled condenser 3 may be used.
  • this invention is constructed so as to have, downstream of condensers 2, 3, a first stop valve 30 which closes at the start signal of the defrosting operation and a constant quantity refrigerant flow-out control mechanism 40 and a constant quantity refrigerant retaining control mechanism these each supplies or retains constant quantity refrigerant in the defrost circuit and to perform the defrosting operation with constant quantity refrigerant, it is possible to perform an optimum defrosting operation irrespective of the operating condition immediately therebefore.
  • the defrosting operation is conducted with optimum quantity refrigerant and no excess refrigerant is circulated, it is possible to save the compressor input that much without the waste of electric energy in the defrosting operation.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Defrosting Systems (AREA)
US06/601,014 1983-04-23 1984-04-16 Refrigeration unit including a hot gas defrosting system Expired - Lifetime US4602485A (en)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP58-71770 1983-04-23
JP7177083A JPS59197764A (ja) 1983-04-23 1983-04-23 冷凍装置
JP58-71773 1983-04-23
JP7177383A JPS59197767A (ja) 1983-04-23 1983-04-23 冷凍装置
JP58-71771 1983-04-23
JP7177183A JPS59197765A (ja) 1983-04-23 1983-04-23 冷凍装置

Related Child Applications (1)

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US06/857,315 Division US4688392A (en) 1983-04-23 1986-04-30 Refrigeration unit including a hot gas defrosting system

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US4602485A true US4602485A (en) 1986-07-29

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US06/601,014 Expired - Lifetime US4602485A (en) 1983-04-23 1984-04-16 Refrigeration unit including a hot gas defrosting system
US06/857,315 Expired - Lifetime US4688392A (en) 1983-04-23 1986-04-30 Refrigeration unit including a hot gas defrosting system

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US06/857,315 Expired - Lifetime US4688392A (en) 1983-04-23 1986-04-30 Refrigeration unit including a hot gas defrosting system

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US (2) US4602485A (fr)
EP (1) EP0123554B1 (fr)
DE (1) DE3474339D1 (fr)

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EP0295894A1 (fr) * 1987-06-15 1988-12-21 Thermo King Corporation Système de réfrigération de transport ayant des moyens pour augmenter la capacité d'un cycle de chauffage
US4831834A (en) * 1987-04-13 1989-05-23 Hoshizaki Electric Co., Ltd. Method of protecting a refrigerating apparatus
US4850197A (en) * 1988-10-21 1989-07-25 Thermo King Corporation Method and apparatus for operating a refrigeration system
US4912933A (en) * 1989-04-14 1990-04-03 Thermo King Corporation Transport refrigeration system having means for enhancing the capacity of a heating cycle
US5056324A (en) * 1991-02-21 1991-10-15 Thermo King Corporation Transport refrigeration system having means for enhancing the capacity of a heating cycle
US6354341B1 (en) 1999-11-10 2002-03-12 Shurflo Pump Manufacturing Co., Inc. Rapid comestible fluid dispensing apparatus and method
US6354342B1 (en) 1999-11-10 2002-03-12 Shurflo Pump Manufacturing Company, Inc. Hand-held rapid dispensing apparatus and method
US6360556B1 (en) 1999-11-10 2002-03-26 Shurflo Pump Manufacturing Company, Inc. Apparatus and method for controlling fluid delivery temperature in a dispensing apparatus
US6397613B1 (en) * 1999-06-25 2002-06-04 Denso Corporation Refrigerating cycle apparatus
US6443335B1 (en) 1999-11-10 2002-09-03 Shurflo Pump Manufacturing Company, Inc. Rapid comestible fluid dispensing apparatus and method employing a diffuser
US6449970B1 (en) 1999-11-10 2002-09-17 Shurflo Pump Manufacturing Company, Inc. Refrigeration apparatus and method for a fluid dispensing device
US6560978B2 (en) 2000-12-29 2003-05-13 Thermo King Corporation Transport temperature control system having an increased heating capacity and a method of providing the same
US6807813B1 (en) 2003-04-23 2004-10-26 Gaetan Lesage Refrigeration defrost system
US20060179874A1 (en) * 2005-02-17 2006-08-17 Eric Barger Refrigerant based heat exchange system
US20060225458A1 (en) * 2005-04-12 2006-10-12 Gaetan Lesage Heat reclaim refrigeration system and method
US20070017249A1 (en) * 2003-09-05 2007-01-25 Daikin Industriest, Ltd. Freezer device
US20070068187A1 (en) * 2005-09-26 2007-03-29 Gaetan Lesage Dual refrigerant refrigeration system and method
CN103429974A (zh) * 2011-02-11 2013-12-04 Frigesco有限公司 闪蒸除霜系统
US20160288619A1 (en) * 2015-04-03 2016-10-06 Tiger Tool International Incorporated Systems and methods for disconnecting a dc load from a dc power source
US9925847B2 (en) 2014-03-10 2018-03-27 Tiger Tool International Incorporated Heating and cooling systems and methods for truck cabs
US11135892B2 (en) 2016-01-25 2021-10-05 Tiger Tool International Incorporated Vehicle air conditioning systems and methods employing rotary engine driven compressor
US11407283B2 (en) 2018-04-30 2022-08-09 Tiger Tool International Incorporated Cab heating systems and methods for vehicles
US11993130B2 (en) 2018-11-05 2024-05-28 Tiger Tool International Incorporated Cooling systems and methods for vehicle cabs
US12030368B2 (en) 2020-07-02 2024-07-09 Tiger Tool International Incorporated Compressor systems and methods for use by vehicle heating, ventilating, and air conditioning systems

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US5669224A (en) * 1996-06-27 1997-09-23 Ontario Hydro Direct expansion ground source heat pump
US20040035136A1 (en) * 2000-09-15 2004-02-26 Scotsman Ice Systems And Mile High Equipment Co. Quiet ice making apparatus
US7017353B2 (en) * 2000-09-15 2006-03-28 Scotsman Ice Systems Integrated ice and beverage dispenser
CN100416191C (zh) * 2000-09-15 2008-09-03 迈尔高装备公司 安静的制冰设备
US8776543B2 (en) * 2008-05-14 2014-07-15 Earth To Air Systems, Llc DX system interior heat exchanger defrost design for heat to cool mode
US9050360B1 (en) * 2010-12-27 2015-06-09 Robert P. Scaringe Apparatus for crankcase pressure regulation using only ambient air or coolant temperature
JP2022103988A (ja) * 2020-12-28 2022-07-08 アクア株式会社 冷蔵庫
CN115950075B (zh) * 2022-12-22 2024-09-24 珠海格力电器股份有限公司 制冷设备的化霜控制方法和装置

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US2451682A (en) * 1946-08-09 1948-10-19 Ole B Lund Refrigeration system using gas for defrosting
US2724245A (en) * 1952-09-30 1955-11-22 Carrier Corp Defrosting arrangements for refrigeration systems
US2718120A (en) * 1953-11-16 1955-09-20 Wilkinson Mfg Company Defrosting refrigeration cycle
US3332251A (en) * 1965-10-24 1967-07-25 John E Watkins Refrigeration defrosting system
US3633378A (en) * 1970-07-15 1972-01-11 Streater Ind Inc Hot gas defrosting system
US3692100A (en) * 1971-07-09 1972-09-19 United Brands Co Mobile refrigerator shipping container unit
DE2604043A1 (de) * 1975-02-05 1976-08-19 Nishinihon Seiki Seisakusho Kk Enteisungssystem fuer eine verdichterkaeltemaschine
US4009594A (en) * 1975-06-02 1977-03-01 Whirlpool Corporation Hot gas defrosting apparatus
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Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4831834A (en) * 1987-04-13 1989-05-23 Hoshizaki Electric Co., Ltd. Method of protecting a refrigerating apparatus
EP0295894A1 (fr) * 1987-06-15 1988-12-21 Thermo King Corporation Système de réfrigération de transport ayant des moyens pour augmenter la capacité d'un cycle de chauffage
US4850197A (en) * 1988-10-21 1989-07-25 Thermo King Corporation Method and apparatus for operating a refrigeration system
US4912933A (en) * 1989-04-14 1990-04-03 Thermo King Corporation Transport refrigeration system having means for enhancing the capacity of a heating cycle
US5056324A (en) * 1991-02-21 1991-10-15 Thermo King Corporation Transport refrigeration system having means for enhancing the capacity of a heating cycle
US6397613B1 (en) * 1999-06-25 2002-06-04 Denso Corporation Refrigerating cycle apparatus
US6354342B1 (en) 1999-11-10 2002-03-12 Shurflo Pump Manufacturing Company, Inc. Hand-held rapid dispensing apparatus and method
US6360556B1 (en) 1999-11-10 2002-03-26 Shurflo Pump Manufacturing Company, Inc. Apparatus and method for controlling fluid delivery temperature in a dispensing apparatus
US6443335B1 (en) 1999-11-10 2002-09-03 Shurflo Pump Manufacturing Company, Inc. Rapid comestible fluid dispensing apparatus and method employing a diffuser
US6449970B1 (en) 1999-11-10 2002-09-17 Shurflo Pump Manufacturing Company, Inc. Refrigeration apparatus and method for a fluid dispensing device
US6695168B2 (en) 1999-11-10 2004-02-24 Shurflo Pump Mfg. Co., Inc. Comestible fluid dispensing apparatus and method
US6354341B1 (en) 1999-11-10 2002-03-12 Shurflo Pump Manufacturing Co., Inc. Rapid comestible fluid dispensing apparatus and method
US6560978B2 (en) 2000-12-29 2003-05-13 Thermo King Corporation Transport temperature control system having an increased heating capacity and a method of providing the same
US6807813B1 (en) 2003-04-23 2004-10-26 Gaetan Lesage Refrigeration defrost system
US20070017249A1 (en) * 2003-09-05 2007-01-25 Daikin Industriest, Ltd. Freezer device
US7640762B2 (en) * 2003-09-05 2010-01-05 Daikin Industries, Ltd. Refrigeration apparatus
US20060179874A1 (en) * 2005-02-17 2006-08-17 Eric Barger Refrigerant based heat exchange system
US7197886B2 (en) 2005-04-12 2007-04-03 Lesage Gaetan Heat reclaim refrigeration system and method
US20060225458A1 (en) * 2005-04-12 2006-10-12 Gaetan Lesage Heat reclaim refrigeration system and method
US20070068187A1 (en) * 2005-09-26 2007-03-29 Gaetan Lesage Dual refrigerant refrigeration system and method
US7401473B2 (en) 2005-09-26 2008-07-22 Systems Lmp Inc. Dual refrigerant refrigeration system and method
CN103429974A (zh) * 2011-02-11 2013-12-04 Frigesco有限公司 闪蒸除霜系统
US9925847B2 (en) 2014-03-10 2018-03-27 Tiger Tool International Incorporated Heating and cooling systems and methods for truck cabs
US10391837B2 (en) 2014-03-10 2019-08-27 Tiger Tool International Incorporated Heating and cooling systems and methods for truck cabs
US20160288619A1 (en) * 2015-04-03 2016-10-06 Tiger Tool International Incorporated Systems and methods for disconnecting a dc load from a dc power source
US11135892B2 (en) 2016-01-25 2021-10-05 Tiger Tool International Incorporated Vehicle air conditioning systems and methods employing rotary engine driven compressor
US11407283B2 (en) 2018-04-30 2022-08-09 Tiger Tool International Incorporated Cab heating systems and methods for vehicles
US11993130B2 (en) 2018-11-05 2024-05-28 Tiger Tool International Incorporated Cooling systems and methods for vehicle cabs
US12030368B2 (en) 2020-07-02 2024-07-09 Tiger Tool International Incorporated Compressor systems and methods for use by vehicle heating, ventilating, and air conditioning systems

Also Published As

Publication number Publication date
DE3474339D1 (en) 1988-11-03
EP0123554A2 (fr) 1984-10-31
EP0123554B1 (fr) 1988-09-28
US4688392A (en) 1987-08-25
EP0123554A3 (en) 1985-05-22

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